Studies on the genetics of aging in a number of organisms including the yeast Saccharomyces cerevisiae, the roundworm Caenorhabditis elegans, and the fruit fly Drosophila melanogaster have revealed the role of metabolic capacity and resistance to stress in determining life span. One mode of modulation of longevity has been suggested to be signal transduction. Signal transduction has emerged as an important molecular mechanism underlying longevity. The results obtained from the study of these organisms are applicable to the dietary restriction paradigm in mammals. It is thought that many of the molecular characteristics identified from these studies will be of interest in determining the effect of diet and signal transduction in the life span of mammals. However, the identification and role of the genes and gene products responsible for modulating the life-span of organism are not yet fully understood. Accordingly, there is a desire to obtain and characterize life-span modulating genes in order to more fully understand the role of stress and life-span.
The effect of genes on life span in Drosophila has been established by selective breeding (Rose et al. Genetics, 97, 173-186 (1981)). However, that methodology involves the participation of multiple genes with additive and quantitative effects that can be difficult to unravel. A more incisive approach is to use single gene mutations. A search for life-extension mutants can lead to the identification of individual genes that regulate biological aging.